Cleaning up toxic solar panels to bring them indoors

Safer and more environmentally friendly indoor solar panels could soon help power electronics in homes and offices, thanks to University of Queensland researchers. A team of chemical engineers led by UQ's Dr. Miaoqiang Lyu and Professor Lianzhou Wang have developed a new fabrication method that eliminates the need for toxic lead and other hazardous solvents in perovskite indoor solar panels. The findings are published in the journal ACS Energy Letters.

"Indoor solar cells themselves are not new, but the power conversion efficiency of the commercial silicon-based technology is only around 10%," Dr. Lyu said. "Halide perovskites are an emerging technology that could replace silicon, offering much higher efficiencies and commercial potential.

"However, most still rely on lead-based hazardous materials. The technology we developed eliminates those materials while still delivering high efficiency."

UQ Ph.D. student Zitong Wang, who is under the supervision of Dr. Lyu and Professor Wang, developed a safe and scalable vapor-based manufacturing process for fabricating high-quality lead-free perovskite material with fewer performance-limiting defects.

Indoor perovskite solar cells operate under low-intensity artificial light, such as light-emitting diodes (LEDs) and fluorescent lamps.

Using the new method, the panels achieved an efficiency of 16.36%—the highest reported for this type of lead-free perovskite indoor solar cell made using an industry-compatible evaporation method.

"This material has very attractive properties that can absorb indoor light and convert very weak indoor light efficiently into electricity," Dr. Lyu said.

"By removing those solvents entirely, the process is much better suited to scalable manufacturing."

Lead-free perovskite indoor solar cells are also increasingly viewed as an alternative to coin-cell and button batteries for low-power electronics like environmental sensors, wearables, medical and health monitoring devices, and small consumer electronics.

Supermarkets trialing battery-powered electronic shelf labels, which replace thousands of paper price tickets and reduce manual labor, are among the potential early applications of the technology.

"With suitable voltage management, these devices can replace coin‑cell batteries, reducing the number of small batteries that end up as waste or in children's toys," Dr. Lyu said.

Panels fabricated using the UQ process are thin, scalable and can be made on flexible plastic and in different shapes, making them easy to integrate into a wide range of products.

The next step is sealing the panels before further testing.

"I think the key here is encapsulation, to protect the material from oxygen and moisture," Dr. Lyu said. "People will probably see perovskite indoor panels and integrated consumer electronics in the market in the next few years."

Provided by University of Queensland